Hi Bob The "ET" designation was generally used for production test, special demo boxes, or other similar uses. My guess is that it was an "in house" unit, and using what was called the "next bench syndrome" may have indeed been the inspiration for the regular production amps.
Daun -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Bob Voelker Sent: Thursday, June 30, 2005 4:15 PM To: [email protected] Cc: [EMAIL PROTECTED] Subject: [time-nuts] HP ET2702 5 MHz distribution amplifier Does anyone have any information, specs, or history of the HP ET 2702 5 MHz distribution amplifier? I suspect that it is a very rare unit, based on the "ET" model number prefix. Could it be the predecessor of the HP 5087A distribution amplifier? I have neither the HP 5087A nor its manual, so here are notes on my ET 2702 for comparison: -One 5 MHz input and ten 5 MHz outputs, all on rear panel. -Front panel has 13 labeled holes for inserting a screwdriver to adjust the gain of each of the 13 amplifier modules inside. -Front panel pushbutton power switch has a guard to prevent accidental shut-off. -Cabinet almost same size as HP 5087A, except for being 5 inches high. -Traditional 1960's HP blue color scheme for cabinet. -Serial number plate on rear does not use the usual HP 1960's or 1970's-on format. The number suggests 1968. -Components inside are date-coded 1968. -Inside, there are 13 unmarked, seemingly identical, fully-shielded amplifier modules of roughly 4 x 2 x 2 inches in size. -Architecture consists of the output of the first amplifier driving the parallel- connected inputs of two following amplifiers, and these amplifiers in turn each drives five amplifiers, providing ten outputs that go to the rear panel. -Each fully-shielded amplifier module has two parallel-connected SMB input jacks, one BNC output jack, and one gain-adjust potentiometer. -Each amplifier module contains two cascaded 2N708 NPN BJT common-emitter amplifiers with the collector of the second stage loaded with a tuned-primary transformer. The transformer's secondary is untuned. -The PCB inside the amplifier module is labeled "05060-6023", suggesting that it might be related to the HP 5060A cesium standard. Thanks for any info, Bob __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
